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Prenatal tests provide largest genetic study of Chinese people

8 October 2018
Appeared in BioNews 970

The largest genetic analysis of China's population to date has been carried out on over 140,000 pregnant women, revealing new insights into migration patterns and disease risk in Chinese people.

The study, published in the journal Cell, harnessed the results of non-invasive prenatal testing (NIPT) which is used in pregnancy to test for fetal abnormalities. It works by collecting small fragments of fetal DNA – known as cfDNA, present in the blood of pregnant women.

In this proof-of-concept study, the cfDNA was used to partially reconstruct the genome of the fetus, allowing researchers to examine it for specific genetic traits and abnormalities.

'NIPT is such a unique opportunity for us to access a large population size,' said Dr Xun Xu, a senior author of the study and president of BGI-Research at BGI-Shenzen, a genome sequencing centre headquartered in Shenzen, China.

'For the first time, we proved that NIPT data can be used in genome-wide association studies to understand the genetic architecture of complex traits and disease,' added Dr Siyang Liu, also at BGI, and first author of the study.

Although these are initial results, the researchers have already been able to use the sequenced genomes to identify genetic patterns in the evolutionary history of China's ethnic groups, as well as discover novel associations between specific genes and physical traits such as height, body mass index and susceptibility to certain viruses.

There are some limitations to the technique however. NIPT does not allow for complete reconstruction of the genome, as the process depends on collecting random fragments of DNA rather than cells with intact nuclei. However, the researchers remain positive that by using such large sample sizes they can still obtain valuable results.

'Although non-invasive prenatal testing is low-pass sequencing, capturing approximately 6-10 percent of the whole genome randomly, there's still a chance that using this data with a large population size will help us to have a much broader vision of what the Chinese genetic population looks like,' said Dr Xu.

NIPT has been primarily used for simpler analyses, such as testing for aneuploidies; genetic disorders where an abnormal number of chromosomes are present in each cell. For example, in Down's Syndrome, there is a third copy of chromosome 21.

With the success of the new study, however, the researchers believe the uses of NIPT will be expanded over the coming years to include comparing the genomes of different populations to gain insights into a wide range of diseases and disorders.

'For me, this is a very exciting new model for biology research,' said Dr Xu. 'It provides powerful tools and a platform for future study. Here, we show proof-of-concept that these data, and the structure and the methods, could be used to study a lot of things. It's just the beginning.'

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